Documents referred to in this specification are as follows. Each Document is referred to by using its Document No.
[Document 1] JP-A-7-30323
[Document 2] JP-A-2000-163544
[Document 3] JP-A-2002-83894
[Document 4] JP-A-2002-269520
[Document 1] discloses that a patch antenna upper electrode is formed on the front surface of a semi-insulating compound semiconductor substrate, a first ground metal is formed on the back surface, the first ground metal is partially removed in an area under the upper electrode of the patch antenna, and an external ground metal constituting a second ground metal is disposed in parallel with the semi-insulating compound semiconductor substrate, being spaced by a constant distance from the back surface of the substrate, to thereby allow radio waves having a frequency of 60 GHz or lower to be irradiated even if the compound semiconductor substrate has a thickness of about 150 μm.
[Document 2] discloses that a processor circuit is formed on the front side of a chip and a coil having a magnetic layer is formed on the back side to thereby prevent crosstalk.
[Document 3] discloses that an antennal coil is disposed not to be formed on an analog circuit to thereby prevent deterioration of the communication performance of a semiconductor chip.
It also discloses that in order to thin a non-contact type semiconductor device as a final product, a thickness of a bare chip is set to 300 μm or thinner, and about 50 μm to 150 μm for a thin type card.
[Document 4] discloses that there is a proportional relation between a thickness of a wireless chip connecting an antenna on the front and back of a substrate and a ground serial resistance of a transponder circuit of the wireless chip, and if the ground serial resistance is small, a communication distance becomes long, whereas if the ground serial resistance is large, the communication distance becomes short because a loss resistance of the circuit becomes large.
However, as illustratively shown in [Document 1] to [Document 4], there is no conventional technical document which studies an extension of a communication distance by thinning a substrate.